Cap and Bridge Combo tripping breaker

[NeilG]

On my Bridgeport mill I replaced the old EZ Track with an Allin1DC system a few years ago. Last week it shut down on its own, everything, while idle, and I found that the circuit breaker on the 110v side of the main power transformer had tripped shutting off control power. It kept tripping when main power was applied but when I disconnected the 110v power lead to the Cap and Bridge Combo, the 110v breaker did not trip and everything else started up. Thinking the Cap/Bridge was the issue, I ordered and installed a new one, but, no luck, the 110v breaker is still tripping.

The Cap/Bridge seems to be cause the control power to trip, but, given that the replacement should be good, now I'm thinking something else possibly related to the Allin1DC is causing this. I'm at loss on where to go next, any thoughts?

Thanks,
Neil

[cncsnw]

What happens if you disconnect the DC wires between the CAPBRDLO and your emergency stop contactor, so that there is no possible load on the CAPBRDLO?

If it starts up okay that way, then reconnect those wires, and disconnect the DC wires between your emergency stop contactor and the VM+ and VM- terminals of the Allin1DC.

[NeilG]

Thanks for the reply. Took your suggestion and disconnected the DC wires from the CAPBRDLO to the E-stop, and then just disconnected them entirely from the CapBrd, I'm still getting the 110v breaker tripping, although at one point the main 208/3ph breaker tripped instead of the 110v control breaker. The only thing that seems to keep either breaker from tripping is to disconnect the AC to the CapBrd.

Would welcome any thoughts.

[centroid467]

You most likely have a short somewhere. Does anything else run from that 110VAC secondary?

[NeilG]

Yes, that 110v powers all the AC loads, the computer as well as the fan and the 5V power supply. When I disconnect the CapBrd they run.

I guess I'll have to keep disconnecting loads to see if there's something else shorting.
Thanks

[NeilG]

I have purchased a new Capboard, installed it and at first was getting my same problem with the AC circuit breaker to the unit tripping. Come to find out that the new Capboard has a contact on the bottom that was not on the old one. When I lift the Capboard enough to prevent that contact from touching the back panel, it no longer trips the breaker. There seems to be direct continuity from the DC (-) terminal to this contact.

Can anyone explain the purpose/correct installation for the new Capboard with the contact on the bottom?

[NeilG]

Further info: Attached photos show the new CapBoard (left) and the original (2015) on right. Note contact on new.

New Capboard on left, original (2015) on right

New Capboard on left, original (2015) on right

[centroid467]

Hello Neil,

I was looking into this for you. There was a part substitution since the old blue capacitor was obsoleted by the manufacturer and it seems that we could only order a compatible part with an unneeded mounting stud. That unexpected contact is the remains of the mounting stud. We have a new part specified to replace this one in future production but I am not sure of the status of that.

At this point the best option is to put several layers of electrical tape over that stud and adjust the mounting location of the CAPBRD to make sure it does not touch anything.